The present invention relates to laminated fiber reinforced composite sheets which can be compression molded and produce smooth glossy surfaces.
The use of glass reinforced thermoplastics for automobile exterior parts is currently being investigated. One approach for producing relatively thin and wide parts such as hoods, roofs and doors is compression molding of composite blank sheets. Experiments conducted to mold shaped panels from conventional glass reinforced blank sheets resulted in panels with surface imperfections. A smooth, glossy surface finish is an important requirement for automobile exterior applications. The surface imperfections were caused by fiber bundles at the surface and voids due to incomplete filling of the mold caused by trapped gas bubbles.
Another technique under development to produce smooth glossy finishes involves a two step operation. The composite is first compression molded and then polymer melt is injected into a very thin space between the mold and the composite.
It is an object of the present invention to provide composite sheets which can be compression molded and produce a smooth glossy surface.
It is a further object of the present invention to provide a fiber reinforced composite sheet which can be used with a single step compression molding cycle to fabricate fiber reinforced shaped composite panels with smooth glossy surfaces.
It is a still further object of the present invention to provide fiber reinforced composite sheets which achieve a smooth glossy surface and reduced thermal shrinkage when compression molded.
It is yet another object of the present invention to provide fiber reinforced composite sheets having high flexural and tensile strengths.